8×8 LED matrix pendant sealed in a block of epoxy

This is the back side of [Dmitry Grinberg’s] 8×8 LED matrix pendant. He had seen the other projects that used a 5×7 grid but wasn’t really satisfied with the figures that can be drawn in that confined area when each pixel has only the option of being on or off. His offering increases the drawing area and includes the ability to display each pixel at several different levels.

He’s using an ATmega328 microcontroller soldered directly to the pins on the back of the LED module. He mapped out the IO in his firmware to make the soldering as easy as possible. To protect the hardware he fashioned a mold around the edges of the LED package using duct tape. The tape held epoxy in place as it hardened, encasing the microcontroller and holding the power wires and ICSP header tightly.

After the break you can see about six seconds of the device in action. The four levels of brightness for each pixel really do make quite a difference!

Yeah, i made a bunch of AVR boards and once i forgot the decoupling on a low power board that was supposed to sleep for extended times. The AVR didn’t draw 10’s of µA anymore, but something like 5mA… The battery ran dry in a couple of days instead of a month.

The AVR will also work at much lower voltages with decoupling, it can happily run under 2V with decoupling (maybe ADC and EEPROM will fail at those voltages though), but will fail miserably and just stop under 3V without decoupling.

I’d have a better video, but I gave the pendant away, and have not yet made a new one. and yes vacuum would have helped – I’ll do that next time. Also sidenote: 4-bit color, not 4 shades. it is 16 shades

I made an oscilloscope / spectrum analyzer pendant that I gave away as a birthday gift. It was a one-off. I used a graphical OLED display and an ATMega328p. I used clear nail polish to seal the components on the back…video at youtube.

I was squinting trying to see the matrix, but laughed aloud when the camera pulled back even farther. Like the thought process was “Oh man, this is too close…I really need a wider shot to set a size comparison here.”